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Endocrinology of Male & Spermatogenesis - Coggle Diagram
Endocrinology of Male & Spermatogenesis
Endocrine control/regulation
Endocrine requirements
FSH and LH secretion from anterior pituitary
LH acts on Leydig cells
Synthesizes progesterone
Converted to testosterone
Secretion of gonadal steroid
Testosterone
Estradiol
GnRH secretion from hypothalamus
Pulses
Testis function requirements
High testosterone in seminiferous tubule
Low testosterone in systemic blood
Pulsatile GnRH secretion
LH receptors in Leydig cells
Production of fertile spermatozoa requirements
Mitotic divisions of spermatogonia
Mitotic divisions resulting in haploid spermatids
Endocrine regulation of testis
Transformation of spermatids to spermatozoa
Sertoli cells
Equivalent to follicular granulosal cells
Convert testosterone to estradiol
Secrete inhibin
Suppresses FSH
Leydig cells
Equivalent to follicular theca interna cells
Synthesize progesterone
Converts to testosterone
Secretes estradiol
Spermatogenesis
Goals
Provide genetic diversity
Provide sperm each day to maximize reproduction
Provide continual supply of male gametes
Provide immunologically privileged site
Proliferation + meiosis + differentiation
Meiotic phase
Primary spermatocyte
Meiosis 1
Secondary spermatocyte
Meiosis 2
Haploid spermatids
Meiotic prophase
Zygotene
Leptotene
Preleptotene
Diplotene
Pachytene
Differentiation phase
Spermiogenesis
Specialized spermatozoon
Flagellum = mitochondrial helix
Principal piece
Head = nuclear material
Deliver male DNA to oocyte
Cap phase
Acrosomic vesicle spreading over nucleus
Acrosomal phase
Nuclear and cytoplasmic elongation
Golgi phase
Acrosomic vesicle formation
Maturation phase
Final assembly that forms spermatozoon
Spermiation
Release of spermatozoa from Sertoli cells
Spermatozoa = head + tail
Head = nucleus + acrosome + post nuclear cap
Acrosome contains hydrolytic enzymes
Zona lysin
Esterases
Hyaluronidase
Acid hydrolases
Acrosin
Tail = capitulum + middle piece + principal piece + terminal piece
Self powered flagellum
9 + 2 microtubules
Proliferation phase
All mitotic divisions of spermatogonia
Stem cell renewal
Result = primary spermatocyte
In seminiferous tubules
Spermatozoa released continually into lumen of seminiferous tubules
Stage duration
Time required to complete one stage
Cycle
Progression through sequence of all stages
Stage
Specific cellular associations
Cycle duration
Time required to complete one cycle
Cycle of seminiferous epithelium
8 stages
Stage 4
1 generation primary spermatocyte
1 generation secondary spermatocyte
2 generations spermatogonia (A+I)
1 generation immature spermatids
Stage 8
1 generation primary spermatocyte
2 generations spermatogonia (A+B)
2 generations spermatids
Stage 1
2 generations primary spermatocytes
1 generation immature spermatids
1 generation A-spermatogonia
Sophomore
Primary oocyte
Junior
Secondary oocyte
Freshman
A-spermatogonia
Senior
Spermatid
Graduation
Spermiation
Spermatogenic wave
Sperm production
Fertility determination
Viability of spermatozoa
Number of abnormal spermatozoa ejaculated
Sperm producing ability
Number of functional/normal spermatozoa ejaculated
Greater testicular circumference = greater sperm production
Sperm motility = viability
Abnormalities
Head
Tapered heads
Ruffled acrosome
Crater defect
Knobbed acrosome
Tail
Coiled tail
Double midpiece
Folded tail
Detached head
Artificial insemination
Steps
Preservation and extension of sperm
In vitro
Insemination of female
Collection of semen
Info needed after collection
Concentration of spermatozoa
Percentage of motile sperm
Ejaculate volume
Total sperm in ejaculation = ejaculation volume + sperm/ml
Good seminal extenders
Isotonic
Good buffers
Provide nutrients
Prevent microbial growth
Minimize cold damage
Low in cost
Maintain viability
Sexed semen
Separation of X and Y bearing spermatozoa
